Method and apparatus for removing debris from cased wells



ETAL 3,500,933

METHOD AND APPARATUS FOR REMOVING DEBRIS FROM GASED WELLS l March 17,1970 .1.1.. BURBA, JR.,

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United States Patent O 3,500,933 METHOD AND APPARATUS FOR REMOVINGDEBRIS FROM 'CASED WELLS John L. Burba, lr., Monahans, and Robert S.Runyan,

Odessa, Tex., assignors to Gulf Oil Corporation, Pittsburgh, Pa., acorporation of Pennsylvania Filed Aug. 16, 1968, Ser. No. 753,180 Int.Cl. E21b 37/00 U.S. Cl. 166-311 7 Claims ABSTRACT OF THE DISCLOSURE Ajunk catcher for use in completing cased wells to be run on drill pipecomprising a pair of wiper cups to remove clinging particles from thecasing wall, and an annular junk accumulation space between an inner mudupliow member and an outer cage member.

This invention relates to oil field equipment, and in particular itpertains to method and apparatus for removing debris from fluid filledwells, particularly oil and gas wells, prior to performing otheroperations in such wells.

During the course of drilling deep wells to petroliferous deposits,debris, junk as it is known in the art, accumulates in the well. As isknown, petroleum wells are at all times full of fluid, usually somesubstance known as drilling mud which comprises a wide range ofrelatively heavy slurries designed to provide a hydrostatic head abovethe pressurized formations which are encountered, lubricate the bitduring drilling, carry the cuttings to the surface, and the like.

The junk with which the invention is concerned comprises bits of cementor concrete resulting from destruction by drilling of floats that mayhave been put in the well for other purposes or from spillage fromcementing operations, bits of various kinds of metal resulting fromexpendable tools and other items left in the well and subsequentlyground to pieces, other foreign matter which may have fallen into thewell, and other miscellaneous and sundry debris which may have found itsway into the well by happenstance.

The pressence of this debris is harmful during completion operations,and other operations requiring that packers be set in the well. Thedebris described, and particularly the smaller particles, cling to theinside surface of the well casing. Such particles and other accumulateddebris interfere with the motion and setting of well packers, resultingin such packers being set prematurely, not setting properly, or beingset at an incorrect height, or the like, resulting in a faultycompletion possibly requiring that the packers be drilled out of thewell.

The present invention comprises a positive action wiper junk catcherwhich is run on drill pipe or drill tubing. Prior junk catchers, or junkbaskets as they are known in the art, are usually run on a wire line.Generically, wire line operation is preferred to operation on drill pipeor tubing because it is easier to simply drop the wire line or rope intothe well than to make a trip with tubular goods. However, it is notpossible to push on a wire or rope, and such prior debris or junkcatchers suffer from the disadvantage that they cannot positively wipethe inside of well casing to push the junk downwardly so that it iseither collected or pushed to the bottom of the well. By the step ofrunning the apparatus of the invention on tubular goods a positivewiping action in addition to collection of the junk is possible. Theincreased cost of running the apparatus of the invention on drill piperather than on wire line is deemed bargain price insurance for atrouble-free completion following the cleaning operation.

Thus, it is an object of the invention to provide a junk 3,500,933Patented Mar. 17, 1970 basket of the character described which compriseswiping means to clean clinging debris from the casing wall and anannular junk accumulation space surrounding an inner upflow cage memberwhich accomplishes a separation of the junk and the well fluid at itsupper end.

ln the accompanying drawing forming a part of this disclosure the solefigure is a cross-sectional elevational view of an apparatus embodyingthe invention shown in place in a fluidand debris filled well.

Referring now in detail to the drawing, 10 designates a petroleum wellwhich has already been cased by well casing 12 in the usual manner. Asis known to those skilled in the art, petroliferous wells are lined orcased with metal pipe known as well casing The casing serves thefunction of preventing cave-ins of incompetent formations that the wellmay have been drilled through, and facilitates completion of wellssince, by perforating the casing, a high degree of control of the amountof product that will be produced is obtained. In any event, the methodand apparatus of the invention is suitable for use with cased wellsonly, and not with the so-called open hole completions wherein theformation is so firm and other conditions are just right that casing isnot required.

The entire length of the inside of casing 12 is filled with a fluid 14,which is usually drilling mud. Partly entrained in mud 14 and partlyadhered to the inside surface of casing 12 are a plurality of particles16 which constitute the debris which is to be removed. These particlesmay be bits of formation, bits of metal, bits of cement or concrete, andother sundry foreign matter. Located in the well is a casing wiping andjunk accumulating apparatus or tool 18 embodying the invention.

Junk catcher 18 is mounted and moved up and down in the well on thelower end of a string of well tubular goods 20 which may comprise drillpipe, drill tubing, or other well tubular goods, dependent upon thediameter required and other factors known to those skilled in the art.

Junk catcher 18 comprises a top adapter or sub 22 comprising a top endinternal thread 24 which cooperates with the male thread or pin at thelower end of the drill pipe 20. At its lower end, top member 22comprises a depending fiange 26 formed with external threads whichcooperate with mating internal threads on an outer cage member 28.

Outer cage 28 makes up the bulk of the length of junk catcher 18. Forexample, in a tool sized for 41/2 to 7 inch LD. (inside diameter)casing, the overall length of the tool will be about 13 feet, 7 inchesand the length of the outer cage will be about l0 feet. In a tool sizedfor 7% to 13% inch I.D. casing, the overall length of the tool will beabout 14 feet 5 inches and the length of the outer cage will be about 10feet.

At spaced locations along the length of outer cage 28 the wall thereofis formed with a plurality of sets of slots 30 each having a iwidthwhich is predetermined to allow free passage of the drilling mud and torestrain passage of debris 16 therethrough. At its lower end, cage 28 isformed with internal threads 32 which mesh with mating external threadson the upper end of a mandrel member 34. Mandrel 34 comprises a topblock portion 36 formed with an upstanding annular flange 38, which onits outside surface has threads icooperating with threads 32 and whichon its inside surface is formed with threads 40 which cooperate withmating threads formed on the lower end of a trap valve pipe assembly 42,described below. The lower end of to-p block 36 is formed with ashoulder 44, at the radial inside portion of which is a dependingmandrel sleeve 46 formed with external threads 48 'at its lower end.Threadedly mounted o-n threads 48 is a hollow nose piece 50, whichserves to guide the tool.

Means are provided to wipe the debris which clings :o the inside ofcasing 12 off of the casing and into the lrillng mud 14, and to causethe mud carrying this .oosened debris and the remaining debris 16already susaended in the mud into the inside of tool 18. To this end, awiper assembly is mounted on mandrel sleeve 46 1nd is held in placethereon between shoulder 44 and :he top of nose piece 50. The wipermeans comprises a gauge ring 52 seated on the top surface of the nosepiece which serves to check the casing size for later packer Jperations.Seated on the upper surface of ring S2 and :losely fitting about mandrelsleeve 46 is a lower spacer sleeve 54 having an upper thinned neckportion 56. The lnside diameter of sleeve 54 is dimensioned so that itfits snugly about the outside diameter of sleeve 46. Mounted Jn lowerspacer sleeve neck 56 is a lower wiper cup 58 which is held in positionon the slight shoulder formed Jetween neck 56 and the body of spacer 54by a lower wiper cup mounting thimble 60. Mounted above lower :himble 60is an upper spacer sleeve 62 formed with an Jpper thinned neck 64. In amanner similar to the lower :up described aibove, an upper Wiper cup 66is held in :lace on the upper neck 64 by means of an upper thimble 58.

The wiper cups 58 and 66 are instrumental in achievng the advantages ofthe invention in that, as the tool is mshed downwardly through casing 12the lower edges )f said cups clean the clinging debris off of thecasing. Additionally, the use of such cups impart substantial/ersatility to a tool embodying the invention in that, Nithin ranges, byusing differing sized cups the same tool :an be used for different sizedcasing. The cups are comnercially available items, one supplier beingGuiberson Division of Dresser Industries, Inc., which supplies the :upsunder the name of packer cups, their type GW. I`he cups are made of wireand rubber. Another advan- :age is that the cups are relativelyinexpensive items, are easily replaced and they absorb most of the abusethat :he tool is subjected to in cleaning a well. By removal of :he nosepiece 50, the two spacer sleeves and the two ;himbles, the cups arequickly and easily renewed at ninimal cost, thus renewing the entiretool.

Means are provided to permit passage of the drilling luid through thetool while trapping the debris which :nters through the bottom open endof the mandrel sleeve 46. To this end, the lower end of valve pipeassembly 42, briefly mentioned above, fits into the inside :hreadedopening on upstanding flange 38 of mandrel 34 within outer cage 28 to aheight thereon spaced somewhat below the upper end of said cage. Thelower end 3f the trap valve assembly is formed with threads which:ooperate with threads 40, and with an upset shoulder 70 to butt againstthe bottom of the mandrel flange. The main body 72 of trap valve 42 isformed with one or more sets of elongated slots 74 each having a width,similar to slots 30, which will permit passage of the well fluidtherethrough while small enough to not permit passage of debristherethrough. In one of the successfully built embodiments of theinvention designed for use in 41/2 to 7 inch LD. casing, slots 30 had awidth of about 3/16 of an inch and slots 74 had a width of about 1/8 ofan inch, with 3 sets of 6 slots each being provided in the Juter cage 28and l set of 6 slots being provided in the trap valve body 72. At itsupper end, valve body 72 is formed with a thickened end 76 comprising anupstanding bifurcated lug 78 to which is hingedly mounted a flappervalve 86 by means of a hinge pin 82.

OPERATION Tool 18 is first mounted on the drill string 20 at the surfacein the normal manner. Tool 18 is then run into the fluid and debrisfilled well as additional lengths or stands of drill pipe are added tomake up the string of drill pipe or other tubular goods. As the tool 18moves downwardly into the well under the influence of the Weight of thestring of tubular goods, the outer edges of the two cups 58 and 66 wipethe entire inside of the casing and urge the debris that was clingingthereto downwardly. All the fluid in the well with the loosened andentrained debris 16 therein will enter the bottom open end of themandrel sleeve 46 and pass upwardly therethrough, taking a path throughthe entire length of the mandrel 34 and then through the entire lengthof the trap valve assembly 42. The speed of passage of the mud with theentrained junk upwardly through the trap valve 42 `will be substantiallygreater than the downward speed of passage of the tool 18 through thewell -because of the decreased cross-sectional area of the trap valvebody 72 with respect to the substantially larger cross-sectional area ofboth the outer cage 28 and the casing 12. This increased speed of flowthrough the innermost part of the tool tends to keep the particles 16 insuspension in the mud. The mud flowing through the tool finally flowsupwardly out of the top thickened end 76 of the trap valve, lifting theflapper valve upwardly by its momentum. Upon exiting from said upper end76, the speed of the debris laden fluid is suddenly decreased because itsuddenly encounters a, larger cross-sectional area, namely the inside ofthe outer cage 28. This sudden decrease in velocity, coupled with therelatively high upward velocity of the debris laden fluid which is aboutto pass by the flapper valve, causes the debris 16 to fall downwardlyunder the combined influence of gravity and the overall downwardvelocity of the tool through the well. The debris collects in theannular space between the outer cage 28 and the trap valve body 72starting at the top of the upstanding flange 38 of the mandrel 34.Another advantage is that substantially only debris collects in theannular space. Thus, the well fluid does not have to filter through theaccumulated debris which could cause clogging of the tool and difllcultoperation. A separation occurs at flapper valve 80, the debris droppinginto the annular space and the -bulk of the well fluid continuingupwardly in the outer cage 28, out through the slots therein, and backto the well.

During this entire stage of debris collection, the well fluid 14 only,and not the debris, was able to flow out of the nested members 42 and 28through the sets of slots 74 and 30 so as to not create excessive backpressures within the tool during its downward passage. Thus, the slotsserve as a pressure equalizer of fluid above and below the movingsealing means 58 and 66.

After the tool has been lowered to a depth well below the depth at whichthe well is to be perforated or otherwise completed, it is simplyremoved from the well by taking apart the string of tubular goods in anormal manner, thereby pulling the tool upwardly outwardly. During thisupward passage through the well, the now cleansed well fluid will passrapidly through the sets of slots 30 and 74 and through the tool, thusequalizing pressure from above to below the moving sealing means 66 and58. After a cleaning operation is completed, and the tool 1s back on thesurface, the accumulated debris is removed by simply opening thethreaded connection between the lower end of the outer cage 28 and theoutside of the upstanding mandrel flange 3S. In the event a great dealof relatively sharp debris was removed and a visual inspection indicatesthat cup renewal is required, the operator simply removes nose piece 50and gauge ring 52, the two spacers, the two thimbles, and the worn wipercups, renews the wiper cups and re-assembles. As is obvious, the entirecleaning, and even the renewal operation if necessary, can be simplycarried out on site by relatively unskilled persons.

While the invention has been described in some detail above, its is tobe understood that this detailed description is by way of example only,and the protection granted is to be limited only within'the spirit ofthe invention and the scope of the following claims.

We claim:

1. A method of cleaning debris out of a iluid filled cased wellcomprising the steps of passing a cleaning tool downwardly through thewell, wiping the inside surface of the well casing with said tool duringsaid downward passage, passing all of the debris-laden fluid in the wellupwardly through a reduced diameter portion of the tool to therebyincrease the speed of passage of the debris laden fluid upwardly throughthe tool, decreasing this upward speed of motion of the debris ladenfluid when it exits from said reduced diameter portion; whereby thedebris will fall downwardly while the well uid continues upwardly atsaid region of speed reduction; additionally permitting the well fluidonly to flow out of said reduced diameter portion of said tool atlocations thereon other than the place of exit of said well fluid andsaid debris therefrom, and collecting the debris in the tool below thetop of said reduced diameter portion.

2. Apparatus cooperable with well tubular goods for cleaning debris outof a fluid filled cased well comprising an imperforate double open endedhollow member adapted to pass well fluid therethrough, wiper means onthe outside surface of said hollow member adapted to wipe debrisclinging to the well casing off of the wellcasing and into the wellfluid, a pair of nested hollow cage members extending upwardly from thetop end of said hollow member, the inside of the inner of said pair ofnested hollow cage members forming a continuation of the passagewaywithin said hollow member and terminating mediately the ends of theouter of said pair of nested hollow cage members, adapter meansinterconnecting the lower end of said well tubular goods and the upperend of said outer member, and valve means at the upper end of said innermember, said valve means opening in response to upward flow through saidinner member.

3. The combination of claim 2, wherein said wiper means comprising upperand lower wiper cups each having an edge portion adapted to contact theinside surface of said well casing, and means to hold said cups inspaced relation to each other along said hollow member.

4. The combination of claim 3, wherein said wiper cups comprise rubber.

5. The combination of claim 3, said spacer means comprising an abutmentshoulder at the upper end of said hollow member, a nose piece threadedlyconnected to the lower end of said hollow member, upper and lower spacersleeves having portions cooperable with Lipper and lower wiper cupholder thimbles, respectively, associated with each of said upper andlower wiper cups, respectively; whereby said wiper cups may be renewedby removal of said nose piece from said lower threaded end of saidhollow member and removal of said wiper cups with their associatedspacer sleeves and holder thimbles off of said lower end of said hollowmember.

6. The combination of claim 2, said hollow member comprising a headportion having an upstanding flange, said flange being formed with screwthreads on its inner and outer surfaces, and said outer and innermembers of said nested hollow cage members being formed with inner andouter surface screw threads, respectively, cooperable with said outerand inner screw threads on said flange, respectively, whereby debrisaccumulated within said apparatus may be removed therefrom by openingthe threaded connection between said outer member and said flange.

7. The combination of claim 2, said nested hollow cage members beingformed with elongated slots, and said outer member being formed withsome of said slots coextensively with said inner member and with some ofsaid slots above the upper end of said inner member, said slots havingwidths predetermined to allow free passage of well fiuid therethroughand to restrain passage of well debris therethrough.

References Cited UNITED STATES PATENTS 1,757,381 5/1930 Morgan et al.

2,290,441 7/1942 McGatfey 166--177 X 2,550,080 4/1951 Moore 166-992,906,341 9/ 1959 Kellner et al 166-99 3,003,558 10/1961 Orr 166-311 X3,016,931 1/1962 Bodine 166-311 X 3,058,525 10/ 1962 Humphries 166--17lCHARLES E. OCONNELL, Primary Examiner JAN A. CALVERT, Assistant ExaminerU.S. Cl. X.R. 166-177

